Magnetic key device

ABSTRACT

A key device for business machines and the like is provided which increases linearly the load smoothly when the key button or knob is depressed and can give a snap action, irrespective of the magnitude of force applied to the key device. The key device comprises a drive member slidably fixed to a retaining member and a follower member which is normally attracted to the retaining member by a permanent magnet. A spring is interposed between the drive and follower members. When the drive member is depressed into the retaining member, the spring is compressed, thereby accumulating the energy. When the accumulated energy overcomes the strength of the permanent magnet, the follower member is immediately pushed outwardly from the retaining member by the spring.

[ Sept. 12, 1972 MAGNETIC KEY DEVICE [72] Inventors: Sigehito Kikuchi; Hiroshi Takeuchi;

Norio Aman, all of Tokyo, Japan [73] Assignee: Nakagima Precision Industries Ltd., Tokyo, Japan [22] Filed: March 30, 1970 [2i] Appl. No.: 23,865

[30] Foreign Application Priority Data April 4, 1969 Japan ..44/30473 June 6, 1969 Japan ..44/44378 Aug. 29, 1969 Japan ..44l8283l Aug. 29, 1969 Japan ..44/82832 [52] US. Cl. ..l97/98, 235/145, 335/206 [5 1] Int. Cl. ..B4lj 5/08 [58] Field of Search ..l97/98; 235/145; 335/206 [56] References Cited UNITED STATES PATENTS 3,363,737 1/1968 Wada et al 197/98 3,457,368 7/1969 l-loucke ..l97/98 X Primary ExaminerEdgar S. Burr Attorney-Flynn & Frishauf 5 7] ABSTRACT A key device for business machines and the like is provided which increases linearly the load smoothly when the key button or knob is depressed and can give a snap action, irrespective of the magnitude of force applied to the key device. The key device comprises a drive member slidably fixed to a retaining member and a follower member which is normally attracted to the retaining member by a permanent magnet. A spring is interposed between the drive and follower members. When the' drive member is depressed into the retaining member, the spring is compressed, thereby accumulating the energy. When the accumulated energy overcomes the strength of the permanent magnet, the follower member is immediately pushed outwardly from the retaining member by the spring.

10 Claims, 13 Drawing Figures PATENTEB 12 I973 3.690.432

sum 2 or 2 Time BACKGROUND OF THE INVENTION The present invention relates to a key device for use in electric typewriters, desk computers, keysets, etc.

The keys for these machines must cause a desired operation irrespective of a magnitude of force applied thereto for depression. There have been proposed keys of the type described with a wide variety of constructions which can satisfy the demands as described above. But recentlydeveloped machines or the like requires the keys to make more complex functions. That is, the load is linearly increased when the key is depressed; the key operates smoothly; and the key must transmit to an operator the feeling or snap action that the key has been depressed to a desired degree. But there has been proposed no key device which can satisfy all of the demands such as described above. It is therefore the broad object of the present invention to .provide a key device whose load upon depression is linearly and smoothly increased and which can provide the snap action and make a desired constant function irrespective of a magnitude of force applied to the key.

It is another object of the present invention is to provide an electronic type contactless key device requiring no power source (which will be referred to as electronic type contactless-non-power key device) comprising the key device in accordance with the present invention and a coil for that the abrupt flux variation in the coil due to the depression of the key may be detected as a voltage variation.

It is a further object of the present invention is to provide an electronic type contactless-non-power key device comprising the key device in accordance with the present invention and a coil so that the abrupt flux variation in the coil due to the depression and return of the key may be detected as a voltage variation. It is a further object of the present invention of the key device of the character described hereinabove which is simple in construction, highly reliable in operation and inexpensive to manufacture. To attain the above and other objects of the present invention, the present invention provides a novel key device comprising a retaining member, a drive and follower members both of which are slidably fixed to the retaining member, the follower member being normally attracted toward the retaining member by a permanent magnet and held in position, the drive and follower members being so arranged as to coact with each other through a spring, the spring being compressed upon depression of the drive member into the retaining member thereby accumulating the energy, that is the returning force, whereby when the energy or the returning force of the spring overcomes the strength of the permanent magnet, the follower member may be immediately pushed outwardly of the retaining member. According to one embodiment of the present invention, a coil is disposed in opposed relation with the follower member on the side of its outward movement from the retaining member.

According to another embodiment of the present invention, a coil is disposed around the outer periphery of the retaining member. Therefore, the flux variation in the coil due to the depression of the key may be detected as a voltage variation or the flux variation in the coil when the key is depressed and returned may be detected as a voltage variation.

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the preferred illustrative embodiments thereof taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING:

FIG. 1 is a front view, partly in section, Jf one embodiment of the present invention;

FIG. 2 is a front view of a drive member thereof;

FIG. 3 is a front view of a follower member thereof;

FIGS. 4A, 4B, 4C and 4D form a sequence line diagram for explanation of the mode of operation thereof;

FIG. 5 is a front view, partly in section, of a second embodiment of the present invention;

FIG. 6 is a front view, partly in section, of a third embodiment of the present invention;

FIG. 7 is front view, partly in section, of a first embodiment of an electronic type contactless-non-power key device in accordance with the present invention;

FIG. 8 is a front view, partly in section, of a second embodiment of an electronic type contactless-nonpower key device in accordance with the present invention;

FIG. 9 is a graph illustrating the relation between the load and time for explanation of the improved characteristics of the key device in accordance with the present invention; and

FIG. 10 is a graph illustrating the output voltage waveform obtained by the electronic type contactlessnon-power key device of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As best shown in FIG. 2, the drive member 24 comprises a stem 28 and a knob 30 integrally fitted over the upper portion of the stem 28 with a pair of spaced apart upper and lower stopper rings 32 and 34 fitted over the stem 28. The stem 28 has a reduced diameter portion 28a. As best shown in FIG. 3, the follower member 26 comprises a stem 36 having a flange 36a formed at the upper end and a blind hole 36b drilled coaxially of the stem 36 and a permanent magnet 38 fitted over the reduced diameter portion 360 of the stem 36. The permanent magnet 38 is rigidly connected to the stem 36 by means of a magnet retainer 40 screwed over the reduced diameter portion 366. These drive and follower members 24 and 26 are fitted into the retaining member 22 from the upper and lower side thereof as shown in FIG. 1. Inassembly, the permanent magnet 38 and the retainer 40 are detached from the stem 36 of the follower member 26 and the stem 36 is fitted into the hole formed through the lower bracket 22 b of the retaining member 22 from the inner side thereof. Thereafter the permanent magnet 38 is fitted over the reduced diameter portion 360 and then the retainer 40 is screwed thereover.

The vertical movement of the follower member 26 is limited to the distance between the flange 36a whose lower surface contacts with the inner surface of the bracket 22b and the permanent magnet 38 whose upper surface contacts with the outer surface of the bracket 22b. The attracting force of the permanent magnet 38 is so selected that the magnet 38 normally attracts the lower bracket 22b, thereby normally holding the follower member 26 in its upper position as shown in FIG. 1.

In assembling the drive member 24, the lower stop ring 34 is removed and then the reduced diameter portion 28a of the drive member 24 is fitted into the hole formed through the upper bracket 22a of the retaining member 22. Thereafter a spring 42 is fitted over the reduced diameter portion 28a and compressed between the stepped portion 28b of the stem 28 and the upper end of the stem 36 of the follower member 26 while the reduced diameter portion 28a of the stem 28 is fitted into the blind hole 36b of the stem 36 of the follower member 26. Thereafter the lower stop ring 34 is fitted over the stem 28. Thus, the drive member 24 is fitted into the hole of the upper bracket 22a of the retaining member 22 slidably relative thereto. This vertical movement of the drive member 24 is limited to a distance between the upper and lower stop rings 32 and 34 and the drive member 24 is normally held in its upper position as shown in FIG. 1 under the returning force of the spring 42.

Next the mode of operation of the first embodiment will be described hereinafter. When the key device 20 is not operated, the relative positions of the components are shown in FIG. 4-A. By depressing the knob 30 by one finger, the drive member 24 compresses the spring 42 thereby charging it. This means that the returning force of the spring 42 is increased. For example when the knob 30 is depressed by a distance H, as shown in FIG. 4-B, the returning force of the spring 42 becomes substantially equal to the magnet strength or attractive force of the permanent magnet 38 of the follower member 26 When the knob 30 is further depressed by a distance h the returning force of the spring 42 overcomes the attractive force of the magnet 38 so that the follower member 26 is immediately forced downwardly by the returning force of the spring 42 as shown in FIG. 4C. Subsequently, in response to the downward movement of the follower 26, the drive member 24 is depressed further compressing the spring 42 by a distance H as shown in FIG. 4-D.

When the finger is released from the knob 30 at its position shown in FIG. 4-D, the follower member 26 is immediately moved upwardly by the force of the permanent magnet 38 so that the drive member 24 is immediately returned to its initial position (FIG. 4-A) through the spring 42.

FIG. 9 is a graph illustrating the relation between the load acting upon the knob 30 and the time. During the time interval from the point E where the depression of the knob 30 starts to the point F where the returning force of the spring 42 becomes equal to the strength of the permanent magnet 38, the spring 42 is gradually compressed as the knob 30 is depressed so that the load exerting upon the knob 30 is linearly increased. At the point F, the returning force of the spring 42 overcomes the force of the permanent magnet 38 so that the follower member 26 is pushed outwardly at high speed as described above so that the load exerting upon the knob 30 is rapidly decreased from the point F to the point G. Since the drive member 24 is depressed further so as to compress the spring 42, the load acting upon the knob 30 is again increased linearly from the point G.

Thus, upon depression of the knob 30, the load is linearly and smoothly increased and a snap action is generated when the follower member 26 is pushed outwardly by the release of the energy stored in the spring 42 so that this snap action remains substantially unchanged irrespective of the force applied to the knob 30. That is, the operator always feels the same snap action.

Since the function of the spring 42 providing this key touch feeling is much affected by the strength of the permanent magnet 38, itis preferable to select the strength of the permanent magnet after a desired design key touch feeling is previously determined.

From the foregoing,'it will be seen that the key device in accordance with the present invention may be applied not only to the business machines but also to a wide variety of fields such as a method for picking up or detecting a voltage utilizing the variation in magnetic flux, the piezo-electric element, the Hall-effect element, etc.

Next the second embodiment of the present invention will be described hereinafter with reference to FIG. 5. In the key device generally designated by 120, a retaining member 122 is different from that of the first embodiment only in that the retaining member 122 comprises a cap body 122a, a magnet holder 122b made of a magnetic material and fixed to the lower end of the cap body 122a and the magnet holder l22b is provided with a recess 1220 formed in the lower surface for receiving therein the permanent magnet 38 of the follower member. The mode of operation of the second embodiment is substantially similar to that of the first embodiment described hereinabove. However, the return of the follower member 26 by the permanent magnet 38 to its initial position can be made at a higher speed and the permanent magnet 38 is attracted only to the magnet holder l22b so that Mylar film or the like is not required to be applied to other magnetic components, thereby enhancing the durability of the device.

Next the third embodiment 220 of the present invention will be described with reference to FIG. 6. The third embodiment 220 is different from the second embodiment shown in FIG. 5 only in that the permanent magnet 38 is fixed to the magnet holder l22b. The mode of operation is substantially similar to that of the first and second embodiments described hereinabove. The special feature of the third embodiment having the permanent magnet 38 securely fixed to the magnet holder 122b lies in the fact that the permanent magnet 38 can be advantageously prevented from the secular variation and especially from de-magnetization due to the cracking, impact, etc.

FIG. 7 illustrates an electronic type, contactless-nonpower key device 320 which is a variation of the devices shown in FIGS. 5 and 6 and has an coil 344 disposed below the follower member 26 for detecting the variation in the magnetic field.

' In an electronic type, contactless-non-power key device 420 shown in FIG. 8 which is a variation of the devices shown in FIGS. 5 and 6, coil 444 for detecting the variation in field isdisposed around the magnet holder 122b and is surrounded by a cover 446. The mode of operation of the devices 320 and 420 is similar to that of the embodiments described hereinabove, but when the follower member is pushed outwardly in the device 320 and when the follower member 26 of the device 420 is pushed outwardly and is returned into the magnetic holder122b, the magnet field is changed and is detected by the coils 344 and 444. The voltage induced in the coil 344 or 444 is given by where d) is the flux in the coil.

It is therefore. necessary that the instantaneous change of the magnetic field will substantially remain constant irrespective of the magnitude of the force applied to. the knob 30. When the key device of the present invention is used, the follower member 26 is pushed outwardly andreturned very rapidly so that a voltage waveform having a sharp rising edge and falling edge-as shown in FIG. 10 may be obtained.

In order to more effectively cause the flux variation in the coil 344 or 444, it is preferable to form a projection 44 at the undersurface of the follower member 26 so as to concentrate the flux and to use a retainer 40 made of a metal having a high permeability. Since the polarity in the devices 320 and 420 may be switched in a simple manner by the key devices 320 and 420, the present invention may be used as an input key for electronic circuits in various fields.

The present invention has been described above with particular referenceto the preferred illustrative embodiments thereof, but it will be understood that variations and modifications can be made without departing from the true spirit of the present invention as described hereinabove and as defined in the appended claims. 3

What is claimed is:

l. A key device comprising:

a retaining member (22, 122) of magnetic material and having a bore therein;

a drive member (24);

a follower member (26), said drive member (24) being slideably and coaxially engaged with said follower member (26) and said follower member (26) being slideably engaged through the bore in said retaining member (22, 122); I

a permanent magnet (38) attached to said follower member (26) and attracting said retaining member (22,122) to serve as the sole force urging said follower member toward said retaining member, said magnet directly contacting said retaining member to retainsaid magnet in position;

a spring (28a) interposed between and urging apart said drive (24) and follower (26) members, said spring being compressed upon depression of said drive member to accumulate energy, said magnet snapping away from said retaining member when said accumulated energy overcomes the attraction force of said permanent magnet to said retaining member, and the magnetic attraction of said magnet to said retaining member serving as the sole returning force when said depression force is released, to return said magnet into direct contact with said retaining member.

2. A key device according to in claim 1 wherein a recess is formed in said retaining member for receiving therein said permanent magnet.

3. A key device according to claim-l wherein said drive and follower members include means to limit movement thereof relative to said retaining member.

4. A key device according to claim 1 including signal generating means spaced from said magnet, said magnet moving toward said signal generating means when snapped away from said retaining member to cause said signal generating means to generate an electrical signal.

5. A key device according to claim 4 including a projection (44) extending from the center of said magnet (38) on the side thereof remote from said retaining member to concentrate the magnetic flux.

6. A key device comprising:

a retaining member 22, 122) of magneticmaterial;

a drive member (24);

a follower member (26) slideably engaged with said drive member (24), said drive member (24) and said follower member (26) being slideably mounted to said retaining member (22, 122) in coaxial relation with each other;

a permanent magnet (38) coupled to said follower member (26) for attracting said follower member (26) toward said retaining member (22, 122) and serving as the sole force urging said follower member toward said retaining member, said magnet directly contacting said retaining member (22, 122) to hold said follower member in position;

a spring (42) interposed between and urging apart said drive member (24) and follower member 26) and being compressed upon depression of said drive member to accumulate energy;

a coil (344) spaced from said follower member (26) and spaced from said magnet (38);

said spring (42) being compressed upon depression of said drive member (24) by a predetermined amount, said magnet (38) and follower member (26) snapping away from said retaining member and moving quickly relative to said coil (344) when the energy accumulated in said spring 42) overcomes the attraction force between said magnet and said retaining member the flux variation in said coil due to the displacement of said follower member and permanent magnet being detected as a voltage variation across said coil, and when said depression force is released, the magnetic attraction of said magnet to said retaining member serving as the sole returning force t 0 return said magnet into direct contact with said retaining member and to return said follower member back to its inoperative position.

7. A key device according to claim 6 wherein said coil is disposed so as to oppose said magnet and said follower member in the direction of movement thereof from said retainer member, said magnet snapping toward said coil when said accumulated spring energy overcomes the attraction force between the magnet and the retaining member to close a magnetic field therewith.

7 8 8. A key device according to claim 7 wherein said when said key device is inoperative. magnet impacts said coil after it snaps away from said A key device according to claim 6 wherein a retaining member.

9. A key device according to claim 6 wherein said coil is disposed around the outer periphery of said 5 retaining member and around said permanent magnet recess is formed in said retaining member for receiving therein said permanent magnet. 

1. A key device comprising: a retaining member (22, 122) of magnetic material and having a bore therein; a drive member (24); a follower member (26), said drive member (24) being slideably and coaxially engaged with said follower member (26) and said follower member (26) being slideably engaged through the bore in said retaining member (22, 122); a permanent magnet (38) attached to said follower member (26) and attracting said retaining member (22,122) to serve as the sole force urging said follower member toward said retaining member, said magnet directly contacting said retaining member to retain said magnet in position; a spring (28a) interposed between and urging apart said drive (24) and follower (26) members, said spring being compressed upon depression of said drive member to accumulate energy, said magnet snapping away from said retaining member when said accumulated energy overcomes the attraction force of said permanent magnet to said retaining member, and the magnetic attraction of said magnet to said retaining member serving as the sole returning force when said depression force is released, to return said magnet into direct contact with said retaining member.
 2. A key device according to in claim 1 wherein a recess is formed in said retaining member for receiving therein said permanent magnet.
 3. A key device according to claim 1 wherein said drive and follower members include means to limit movement thereof relative to said retaining member.
 4. A key device according to claim 1 including signal generating means spaced from said magnet, said magnet moving toward said signal generating means when snapped away from said retaining member to cause said signal generating means to generate an electrical signal.
 5. A key device according to claim 4 including a projection (44) extending from the center of said magnet (38) on the side thereof remote from said retaining member to concentrate the magnetic flux.
 6. A key device comprising: a retaining member (22, 122) of magnetic material; a drive member (24); a follower member (26) slideably engaged with said drive member (24), said drive member (24) and said follower member (26) being slideably mounted to said retaining member (22, 122) in coaxial relation with each other; a permanent magnet (38) coupled to said follower member (26) for attracting said follower member (26) toward said retaining member (22, 122) and serving as the sole force urging said follower member toward said retaining member, said magnet directly contacting said retaining member (22, 122) to hold said follower member in position; a spring (42) interposed between and urging apart said drive member (24) and follower member (26) and being compressed upon depression of said drive member to accumulate energy; a coil (344) spaced from said follower member (26) and spaced from said magnet (38); said spring (42) being compressed upon depression of said drive member (24) by a predetermined amount, said magnet (38) and follower member (26) snapping away from said retaining member and moving quickly relative to said coil (344) when the energy accumulated in said spring (42) overcomes the attraction force between said magnet and said retaining member the flux variation in said coil due to the displacement of said follower member and permanent magnet being detected as a voltage variation across said coIl, and when said depression force is released, the magnetic attraction of said magnet to said retaining member serving as the sole returning force t o return said magnet into direct contact with said retaining member and to return said follower member back to its inoperative position.
 7. A key device according to claim 6 wherein said coil is disposed so as to oppose said magnet and said follower member in the direction of movement thereof from said retainer member, said magnet snapping toward said coil when said accumulated spring energy overcomes the attraction force between the magnet and the retaining member to close a magnetic field therewith.
 8. A key device according to claim 7 wherein said magnet impacts said coil after it snaps away from said retaining member.
 9. A key device according to claim 6 wherein said coil is disposed around the outer periphery of said retaining member and around said permanent magnet when said key device is inoperative.
 10. A key device according to claim 6 wherein a recess is formed in said retaining member for receiving therein said permanent magnet. 